Electric heater



Sept. 18 1923. 1,468,106 v w. s. HADAWAY, JR

ELECTRIC HEATER 3 vwewfoz MM; M

WMQ-MW Sept..18, 1923.

W. S. HADAWAY, JR

ELECTRIC HEATER Original Fi 1ed na 23, .1917 2 Sheets-Sheet 2 anve'wl'oz a attorney; 3% WM +-M Patented Sept. 18, 1923- UNITED, STA

WILLIAM S. HADAWAY, JR, OF NEW ROCHELLE, NEW YORK.

ELECTRIC HEATER.

Application filed Kay 23, 1917, Serial No. 170,859. 7 Itenewed August 5,1921. Serial No. 490,109.

To all whom it may concern:

'Be it known that 1, WILLIAM S. Hana- WAY, J r., a citizen of the UnitedStates, and a resident of New Rochelle, county of vWestchester, andState of New York, have invented certain new and useful Improvements. inElectric Heaters, of which the following is a specification, referencebeing had to the accompanying drawings, forming a part thereof. .s

My invention relates to electric heaters and heater units or structuresand it has special reference to such as are adapted and intended to beput to a wide variety of uses without material change in the structureof the heater. In other words, my invention has reference to a heaterelement or fundamental member which leads itself to general use in thearts.

One object. of m invention is to provide a heater element 0 theaforesaid character, that shall be adapted to' utilize effectively bothalow cost source of heat such as lowpressure steam, and, a'relativelyhigh cost 2 source such as electricity.

.Another object is to concentrate the heat at any particular part orportion of the I heater and to minimize the heat losses when the deviceis in service.

Another object is to provide a heating element that shall not onl ruggedlike the armore type as hitherto constructed, but furthermore one inwhich the necessity for high pressure between the heat generatingelement, its insulation and the sheath is avoided and the heat istransferred to the sheath by a particularly effective medium which isnot hindered by the electrical insulation disposed between thegenerating element and the sheath.

. The requirements of the design of an electric heater suitable for useon a circuit of ordinary voltage, are such that it is very diflicult andoften expensive to produce a '46 heater which effectively supplies heatto a small area such as the point of a small soldering iron or the endof abranding tool or the like, and low voltage windings have beenemployed in some cases, the line voltage being reduced by translatingdevices such as transformers, motor generators, etc.

be mechanically- It has been my aim to provide a heater,

element that shall automatically build up its seat to ahigh temperatureand concentrate it at a small area, at one end for example, without theuse of a translating device such as a transformer or other means forapplying low voltage current to the heater. i

In order that my invention may be thoroughly understood 1 Will nowproceed to describe the same in the'following specification, and thenpoint out the novel features thereof in appended claims.

Referring to the drawings:

Figure 1 is an elevation of a heater element or unit constituting anembodiment of my invention.

Figure 2 is a longitudinal section of the same unit as adapted to theuse of a'branding tool or iron but drawn to a relatively large scale toshow the details of the structure.

An end view of the same is shown in Figure 3. v

Figure 4 is a transverse "section on the line 4-F4 of Figure 2.

1 working ends of the heater units modified for use as a soldering tooland as a cautery. Figure 7 corresponds 'to Figure 2 and shows a modifiedstructure which also constitutes an embodiment of my invention. Figure 8is a section taken on the line 88 of Figure 7 One of the .units is shownas adapted for use as a pyrographicinstrument in Figure 9. 4 Figure 10is a bottom plan view, the handle and casing omitted, of a, laundry ironprovided with the heater units or elements of my invention.

Figure 11 is a sectional elevation of the same men. I i I Figure 12 is apartially sectional plan view of the iron, with the electric circultconnections shown diagrammatically.

Figure 13 shows one of the heaters as applied to the iron, inlongitudinahsection, and I Figure 14 shows the same heater in transversesection. v

res 5 and 6 are sections showing the.-

- is supplied from the conductor 17 for ex Figure 15 corresponds toFigure 2, and shows still another modification of my invention.

Special reference may first be had to Figures 1 to 1 inclusive, fromwhich it appears that the unit or heater element comprises an elongatedtubular casing or armor 10 of metal, an inner tubular member 11 which issubstantially coextensive with the casing, and is smaller in diameterbeing spaced therefrom by an insulating granular mass 12 which may becomposed of particles of carborundum. Within the inner tube is anelectric heating coil 13 which is connected at the working end of thedevice to the inner tube 11, and is separated from the inner tubethroughoutits length by finely divided insulating particles 1 which mayconstitute a porous or granular mass similar to the mass 12.

The coil may extend the entire length of the structure but it may bepreferable in many cases to make it somewhat shorter than the tubes andlocate it adjacent to the working end of the device which is designated15. in the structure illustrated in Figures 1 to i, the working memberis formed into .a branding die 16.

The tube 11 constitutes one of the electrical terminals of the device, asupply circuit conductor 17 being connected thereto. The terminal 18 or"the coil 13 constitutes the other terminal of the device and isconnected to a supply circuit conductor 19. The inner tube 11 extendsslightly beyond the casing and is connected to a pipe 20 through whichlow temperature steam or other suitable fluid is supplied to the device.

The unit, as already explained, will usually be long relative to itsdiameter and as hereinafter explained, it may be bent into anyconvenient form such as a helix or spiral in' order that it may be morecompact and better adapted for use in the arts.

When the device is in use, electric energy ample, thrhugh the tube 11 inwhich more or less heat is generated, thence through the c011 13 inwhich a large proportion of the heat is generated, then through theterminal 18 to the conductor 19. The fluid supplied to the unit may be apermanent gas as air, but I prefer to utilizelow pressure steam whichmay enter for example, at a temperature of 225 F;

This steam percolates through the porous mass 14 formed by the granularparticles within the inner tube and heats the mass to its owntemperature. iAs the steam pro-.

gresses its temperature is very materially increased by taking up theheatgenerated in the coil 13 and 111 the tube 11. This heat iscumulative, the temperature of the steam being built up until it finallyemer s through a screen 37 at the working end df the inner tube into thecasing at the temperature desired to produce the best working results.

The heat is given up to the work and the temperature of the steam isreduced at this point to some extent. It then flows backwardly throughthe porous mass 12 in the casing. This mass 12 is an insulating masswhich prevents the short-circuiting of the inner tube and coil to thecasing and it is heated by the steam to a relatively high temperatureand hence operates very efiectively in preventing loss of heat from thetube and coil in which it is generated electrically.

Steam in passing back to the casing is at a suificiently hightemperature to give up heat to the incoming steam. This heat transfertakes place to a greater extent as the steam travels away from theworking member, and it will be clearly understood that a largeporportion of the heat remaining in the steam as it passes through thecasing is taken up by the incoming steam as it enters the inner tube. Bythis means the steam which finally escapes from the casing at 22 througha screen 38 is only slightly higher in temperature than the steam whichis supplied to the inner tube.

It is therefore evident that the loss of hea when the structure is inuse, is very slight. lVhen the device is not in use the electric energymay be shut oil and the steam allowed to percolate through the tool. Thesteam constitutes a relatively low cost source of heat and without theuse of electric current will maintain the tool at a temperaturematerially above that of the atmosphere. In many classes of workthestandbylosses under ordinary conditions are relatively great whenelectricity is utilized as the sole source of heat.

A particularly important feature of my inventidn however, is the rapidand effective concentration of heat at the working member even thoughthe member may be small in size. It is for this reason that thestructure of my invention overcomes the usual difficulties of providingelectric heaters for small tools and like purposes, and avoids theexpense usually involved inresorting to translating devices as alreadyexplained.

Attention is directed to the fact that I do not depend upon conductionthrough metal to carry heat to the working member and the working membermay of course be formed in various ways. It may constitute a solderingpoint 21 as shown in Figure 5, or a cautery 23 as shown in Figure 6. Theheat is supplied as fast as required by'the flow of the steam or otherfluid which constitutes a,heat carrier. 7

In addition to the aforesaid advantages the exchange of heat between theoutgoing vapor in the outer casing and the incoming vapor is highlyimportant and advantageous.

Still further advantages which will be readily understood by thoseskilled in this art are-secured by my present invention on account ofthe simplicity of the structure itself and on account of the fact, thatthe heat is effectively transferred from the heat generating elements tothe casing or armor without the necessity of subjecting any of the partsto compression.

While my invention is well adapted to concentrate heat at a very smallarea such as at the end of the unit, it is by no means limited in thisregard, and it will be understood that heat is transferred to the casingor armor 10 from which heat may be taken for any useful purpose. If theheat is only to be utilized near the end of the structure the remaindermay of course be covered by a suitable heat insulation designated 24 inFigure 6.

The forming of the unit into a coil is illustrated in Figure 9, the coilis designated 25 and the point of the instrument which may be adaptedfor pyrographic work, is designated 26. The coil is provided with atubular casing 27, the fluid supply pipe being designated 28, and theelectrical conducting leads 29.

The structure of the unit or element may be varied within the spirit andscope of my invention. For example, attention may be directed to Figures7 and 8 in which the electrical heat generating unit comprises an innertubular member which is bent into U- shape and is perforated at or nearthe bend in the U as indicated at 31. The two branches of the tube areelectrically separated by a porous insulating mass 32 which correspondsto the mass 12, andthe ends of the tube are connected electrically tothe circuit conductors 17 and 19 and mechanically to the steam inletpipe 33.

The tube is surrounded by a casing or armor 34 corresponding to thearmor 10. The end of the unit is shown enlarged at 35 to constitute astove or aheater for any suitable purpose. The tube 30 may be flattenedas shown in Figure 8 so that the casing may be circular in form withoutmaterial waste space within. In this case the returned vapor escapes at22 through the screen 39.

Still another modification of my invention is shown in Figures 13 and 14which comprises an outer casing and a pair of inner tubes 41 and 42,which are spaced apart and from the casing by amass 43 of insulation.Each of the tubes is formed to correspond to the inner tube 11. The tube41 for example,

is closed at one end except for perforations 44 and has a heating coil45 within it and connected to it near its perforated end. The coil iselectrically separated from it except at the point of connection by aninsulating mass 46 correspondingto the mass 14.

Within the same outer casing 40 there are two tubes and two coils"and'they' may be connected electrically in series as clearly' shown inFigure 13 or in any other suitable relation. The structure shown inFigures- 13 and 14 may be utilized in various ways. It may for example,be applied to an electric laundry iron'as shown in Figures 10, 11 and alaundry iron and it is particularly difficult to accomplish this'resultbecause of the constant demand for heatat this point.

By utilizing a pair of heater structures of the character just describedand bringing their hot ends together at the point of the iron, a hightemperature/is produced and maintained at the point. As shown in Figures10, 11 and 12, there are two lengths of tubular casings 4O curved tocorrespond to the curvature of the body of the iron into which the unitsare cast.

In casting'the body 47 of the iron the tubes 40 are arranged with theiropen ends extending into a pocket or chamber 48 near the pointof theiron. Atthe heel of the iron the tubes 40 are bent upwardly and. comeout of the casting at the top. The inner tubes 41 and 42 are joined byaconnecting tube 50 to which a fluid supply pipe 51 is connected.

The tubular casings 40 open into a chamher or jacket 52 which is formedby a'cov'er plate 53 of the iron. This chamber is sealed except near thepoint of the iron where it opens through a narrow channel 54 anddischarges downwardly onto the work.

The pipe 51 may have'the form of a fiexi ble tube and steam is suppliedtherethrou-ghto the inner tubes 41 and 42. It flows forwardly throughthese tubes and; is he'ated't high temperature by' the electric heatingelements comprising the tubes themselves and the coils 45. It is finallydischarged into the chamber 48 and then flows back through the tubularcasings 40, giving up its heat to the iron and also preheating theincoming vapor. It is finally discharged into the chamber 52 and throughthe passage 54 onto the goods. I

If the ironing operation is-ju-st' begun and the gddds are cold. thevapor will be conden sed and the goods will be moistened, thus avoidingthe necessity of moistening in advance. When the goods are heated andthe ironing operation is practically complete the hot steam which isstill at asuliiciently-high temperature to be dry, is discharged withouthaving any material efi'e'ct on the goods. I As further indicating thescope of my inlike.

for example, in small furnace work, or the like, I prefer to employ forat least a portion of the structure, elements which are better adaptedthan ordinary metals to withstand the high temperature conditionsimposed.

As shown in the drawings 60 designates the metallic portion of the outercasing and-61 the high temperature portion which may be formed of a.quartz tube, a fulgarite or the This tube is joined in some suitablemanner to one end of the metal tube 60, the sleeve 62 being indicated asa convenient means for this purpose. Within the casing is a relativelysmall tube 63 which corresponds to the tube 11 of Figure 2 and which maybe formed into a coil as shown in order to increase its length relativeto the metal casing 60.

Joined to the inner tube 63 is a tubular member 64 which may be formedof molybdenum, tungsten or like material. In some instances this hightemperature section of the inner tube may be formed of some suitablefulgarite which will act as a conductor when its temperature issufliciently high. The device further comprises an electric heater. 65which may correspond to the coil lation.

13 of Figure 2 and one terminal 66 of which extends throughthe tube 63and the other terminal may conveniently be wrapped around the molybdenumor tungsten element 64: and then brought back through the casing sectionto the terminal end 67.

In the casing member 60 I have shown vapor taps 68 and 69 to whichsuitable tubes or pipes 70 and 71 may be connected.

The electric heater is spaced from the inner tube and the inner tube isheld in position and spaced from the casing by a porous mass 7 4 ofsuitable insulating material which may consist ofv carborundum particlesin granular form as already described in connection with the arrangementshown in Figures 1 and 2.

The concentration of heat is not only effected by the flow of the vaporwhich carries the heat towardcthe hot end of the device. but may also beconsiderably assisted by the positive temperature coefficient of theelectric'heater under the influence of the temperature produced by thevapor accumu- The concentration .of heat may be still furtheraugmentedby making the insulating mass through which the vapor must percolate,finer; grained near or at the high temperature portions of the device.For example, the casing section 61 and the inner tube section 64 whichmake up the hot end of the device illustrated, may be filled with grainsor particles designated 75 which are finer than those in the sections 60and 63 where the temperatures are comparativel low and where the designmakes it practlcable to largely increase the surface of the inflowingtube compared to that of the outgoing vapor. 1

For example, the inner tubular member 63 may be coiled within the casingas shown, in order to increase the length of the path and the resistanceto the inward flow relative to the outward floiv of vapor through thecasing section 60. Under these conditions it will be desirableto permitthe vapor to fiow' more rapidly through the outer casing and hencelarger insulating particles maybe advantageously used as aboveindicated.

The tubes 68 and 69 may be used as independent sources of hot vapor,their temperature depending on the position of the taps, or they may beemployed as an inlet and the other as an outlet for supplying heat fromsuperheated steam or some other available source which is at anintermediate temperature between the incoming vapor supplied to theinner tube 63 and the working temperature of the device.

It is evident that while I have only illustrated a few Ways in which theheater element of my invention may be employed, it is capable of verywide application, and I intend that only such limitations be imposed asare indicated in the appended claims.

What I claim is: I

1. A heater comprising a heat intensifying member having a fluidpassage. means for electrically generating heat therein. and an outercasing adapted to provide a heat exchange chamber.

2. A heater comprising a heat intensifying member having a fluid passageand means for electrically generating heat therein, and an outer casingadapted to provide a heat exchange chamber communicating with the fluidpassage and constituting an outlet therefor.

3. A heater comprising a heat intensifying member having a relativelylong fluid passage and means for electrically generatlng heat therein,and an outer casing coextensive with the intensifying member and spacedtherefrom to provide a heat exchange chamber. I

4. A heater comprising aheat intensifying member having a relativelylong fluid passage and means for electrically generating heat therein,and an outer casing coextensir-e with the intensifying member and spacedtherefrom to provide a heat exchange chamher, said casing beingconnected to the fluid passage at one end-whereby fluid may pass throughthe passage and return through the exchange chamber. 1

5. A heater comprising a heat intensifying member having a fluidpassage, heat absorbent material therein adapted to permit the gradualflow of fluid therethrough, means for electrically generating heat inthe passage, and. an outer casing adapted to provide a heat exchangechamber.

6. A heater comprisin a heat intensifying member having a fluid passage,heat absorbent material therein adapted to permit the gradual flow offluid therethrough, means for electrically generating heat in thepassage, an outer casing, interposed insulatin material adapted topermit the flow of flui therethrough, whereby the outer casingconstitutes an exchange chamber.

7 A heater comprising an elongated heat intensifying member having afluid passage, means for electrically generating heat therein, an outercasing coextensive with the heat intensifying member, interposed porousinsulation for electrically separating the easing from the heatintensifying member. said passage being in communication 'with thecasing, so that the CflSlIlg'CDIlStltlltQS a heat exchange chamber.

8. A heater comprising an elongated heat intensifyin member having afluid passage, means for e ectrically generating heat therein, an outercasing coextensive with the heat intensifying member, interposed porousinsulation for electrically separating the casing from the heatintensifying member, said passage being in communication with the casingat one end whereby fluid may pass through the passage in one directionand back through the casing in the opposite direction.

9. A heater comprising an elongated heat intensifying member havmg afluid passage,

a porous heat absorbent material within the passage, means forelectrically generating heat in the passage, an outer casing coextensivewith the heat intensifying member, and interposedporous insulation forelectrically separating the casing from the heat intensifying member,said passage being in communication with the casing so that the cas:

ing constitutes a heat exchange chamber.

10. A heater comprising an elongated heat intensifying member having afluid passage, a porous heat absorbent material within the passage,means 'for electrically generating eat in the passage, an outer casingcoextensive with the heat intensifying member, interposed porous.insulation for electrically separating the casing from the heatintensifying member, said passage being in communication with the casingat one end, whereby fluid may pass through the passage in one directionand back through the casing in the opposite direction.

11. A heater comprising an electric heating element, a sheath or armorin which the heater is disposed, porous insulation between the heaterand the sheath, and means with which the heating element is associatedfor conducting hot vapor through the device to rapidly increase thetemperature and then through the insulation to transfer the heat to thesheath and preventrloss of heat from the. element.

12. A heater comprising an inner conductor constituting an electricheating element and a fluid inlet pipe, means in the pipe to retard theflow of vapor therethrough, an outer sheath spaced from the innerconductor and connected thereto at one end, and insulating means betweenthe inner conductor and the sheath adapted to permit the flow of vaportherethrough.

13. A heater comprising an electric heating element forming an innerpassage through which hot vapor may be supplied, porous insulationsurrounding the heating element, and a. sheath forming a vapor chamberand spaced from the heating elemeht by the orous insulation.

14. A heating element adapted to dissipate heat comprising an outer metasheath or armor, an electric heating element within, and interposedporous insulation, said heater constituting-means' for conducting heatedvapor into the element, and said sheath constituting means for leadingvapor away, whereby the heat is transferred from the heating element tothe, sheath by the vapor and whereby .the vapor prevents loss of heatfrom the element. 1

15. A heater comprising an electric heating element, a vapor inletpassage receiving heat from the heating element, a heat conductingsheath comprising an outlet passage and porous insulation in the outletpassage to support the electric heating element without prevening theflow of vapor through the outlet passage.- I

16. A heater comprising an elongated heated tubular resistance element,a sheath of conducting material surrounding the 613-.- ment andinterposed porous insulation, said tubular resistance" element being incommunication with the sheath at one end whereby vapbr may be suppliedto the heater element, then flow slowly through the insulationto'transfer heat to the sheath.

17. A heater comprising a heat intensifying member having a fluidpassage, means for generating heat in one portion of said passage, andan outer casing adapted to having a relatively low temperature heat 130exchange section and a high temperature fluid passage heat intensifyingsection, means for generating heat in the heat intensifying section, andan outer casing arranged to provide a return passage for the fluidadjacent to the heat exchange section of the inner member.

20. A heater comprising an inner tubular member having a heat exchangecoil, and a high temperature section, means for generating heat in thehigh temperature section, a casing having a high temperature workingmember surrounding the heat intensifying member Within, and a heatexchange section surrounding the coil of the inner member, said casingproviding a return connection for the fluid.

21. A heater comprising a tortuous fluid passage, a heat intensifyingmember connected thereto, an electric heater for gencrating heat in theheat intensifying member, a casing surrounding the inner member andinterposed porous insulation for spacing the casing therefrom.

22. i heater comprising a tortuous fluid passage, a heat intensifyingmember connected thereto, an electric heater for generating heat in theheat intensifying member, a casing surrounding the inner member andcomprising a high temperature working section of refractory material,and a relatively low temperature heat exchange section of metal, andmeans for separating the casing from the inner member without preventingthe flow of heat carrying fluid therethrough.

23. A heater comprising a heat intensifying member having a fluidpassage, means for electrically generating heat therein, an outer casingadapted to provide a heat exchange chamber, and spaced taps in said heatexchange member.

24. A heater comprising a heat intensifying member having a fluidpassage,heat absorbent material therein adapted to permit the gradualflow of fluid therethrough, means for electrically generating heat inthe passage, an outer casing adapted to provide a heat exchange chamberand a porous mass offering a graded resistance to the return flow ofvapor through the casing.

25. A heater comprising a heat intensifying member having a fluidpassage, heat absorbent material therein adapted to permit the gradualflow of fluid therethrough, means for electrically generating heat inthe passage, an outer casing, interposed insulating material adapted topermit the flow of fluid therethrough, whereby the outer casingconstitutes an exchange chamber, said interposed insulating materialbeing arranged to concentrate the heat at a predetermined portion of thecasing.

26. A heater comprising a heat intensifying member having a fluidpassage, heat absorbent material therein adapted to permit the gradualflow of fluid therethrpugh,

means for electrically generating heat in the passage, an outer casing,interposed insulating material adapted to permit the flow of fluidtherethrough, whereby the outer casing'constitutes an exchange chamber,said interposed insulating material being composed of a fine grainsection to concentrate the heat and a coarser grain section to permitthe flow of fluid therethrough.

27. A heater comprisin a heat intensifying member having a fluidpassage, an electric heater within the passage having a positivetemperature coeflicient, and an outer casing adapted to provide a heatexchange chamber.

28. A heater comprising a heat intensifying member having a relativelylong fluid passage, an electric heater within the passage having apositive temperature coeflicient and an outer casing coextensive withthe intensifying member and spaced therefrom to provide a heat exchangechamber, said casing being connected to the fluid passage at one endwhere-by fluid may pass through the passage and return through theexchange chamber.

29. A heater comprising a tubularbody having a tool or working memberconstituting a closure at one end of the tube, an inner tubular memberadapted to discharge heating fluid into the outer member near the tool,and means for generating heat in the inner member.

30. A heater comprising an outer member having a discharge opening atone end and a working member or tool at the opposite end, a heatingfluid conductor extending. close to the working member or tool withinsaid tubular member, and means for generating heat in the inner member.

31. A heater comprising an outer member having a discharge opening atone end and a working member or tool at the opposite end, a heatingfluid conductor extending close to the working member or tool withinsaid tubular member, and means for electrically generating heat in theinner member so as to cumulatively increase the'temperature of theheating fluid.

32. A heater comprising an outer membe hvaing a discharge opening at oneend and a working member or tool at the opposite end, a heating fluidconductor extending close to the working member or toolwithin saidtubular member, an insulating mass adapted to hold the inner and outermembers in spacedrelation, said mass being porous to constitute meansfor retarding the flow of the heating fluid. I

33. A heating tool comprising a tubular body having a working member atone end, an inner heating fluid conducting tube extending intothetubular body and adapted to discharge close to the working member,in-

terpose granular insulation for retarding I the not be heating fluid andspacing the outer from the innermember. anelectric conductor-'connected' to the tubular member at its inner end and imbedded in theinsula'ting material, said electric conductor and body having a workingmember atone end, an nner heating fluid conducting tube extendin intothe tubular body and adapted todisc ar e close 'to the working member,

fine-- granu a'r' insulation between the discharge end of the inner tubeand the workingmember' and relatively coarse granular insulatingmaterial between the outer and innertubular members, and meansco-operatin with the inner tube for establishing an e ectric heatgenerating circuit.

35."A heater comprising a tubular body having a working member at oneend and a discharge outlet at the opposite end, a tubular inner memberof U-shaped formation, perforated at the bend of the U and extendinginto the outer tubular body close to the working member thereof, meansfor supplying heating fluid to both branches of the U-shaped innermember, and means for establishing a heat generating circuit throughsaid inner member.

36. A heater comprising a tubular body having a working member at oneend and a discharge outlet at the opposite end, a tubular inner memberof U-shaped formation, erforated at the bend of the U and exten ing intothe outer tubular body close to the working member thereof, means forsupplying heating fluid to both branches of the U-shaped inner member,means for estabsaid inner member, and porous heat insulalishing aheatgenerating circuit through tion interposed between the inner and outermembers and constituting means for retarding the flow of the heatingfluid.

37. A heater comprising a tubular body of circular section having aworking member at one end and a dischage outlet at the opposite end, atubular inner member of U- s'haped formation flattened in section,perforated at the bend of the U and extending into the outer tubularbody close to the working member thereof, means for supplying heatingfluid to 'both branches of the U- shaped inner member, means forestablishing a heat generating circuit through said inner member, andporous heat insulation interposed between the inner and outer membersand constituting means for retarding the flow of the heating fluid.

'38. Ina heating tool, a heat generating element, means for conducting aheat transferring medium from said element to a desired portion of saidtool, and means for discharging said medium upon the work.

39. In a heating tool, a heat generating element, means for conducting avapor from said element to a desired portion of said tool whereb heat istransferred thereto, and means or discharging the vapor upon the'work.

40. A heating tool comprising means for injecting a vapor into saldtool, a heating element for raising the temperature of the vapor, avapor conductor adapted to conduct the heated vapor to a desired portionof the tool, and means for discharging the vapor upon the work.

41. A heater comprising a casing, a heat generating element, means forcirculating a heat transferring medium within said casing, and a porousmaterial for maintaining said element positioned within said casing forretarding the circulation of the medium.

42. A heater comprising a casing, a heat generating element, means forcirculating a heat transferring medium within said casing, and a porousmaterial for maintaining said element positioned within said casing forconcentrating the heat at a desired portion of said casing.

43. A heater comprising a casing, a heat generating element, means forcirculating a heat transferring medium withln said casing, and a porousmaterial for maintain-.

a fluid inlet conduit, and meansfor returning the heated fluid along theoutside of the conductor.

47 Intercommunicating inlet and outlet heat exchange conduits and anelectrical heater integrally combined with' the inlet conduit.

48. Intercommunicating inlet and outlet heat exchange conduits, a heaterin the inlet conduit, and' means in at least one of said conduits forbreaking .up the fluid and retarding the flow thereof.

49. Interoommunicating inlet and outlet heat exchange conduiw, a heaterin the in let conduit, and means in said conduits for breaking up thefluid and retarding the flow thereof.

50. Inlet and outlet heat exchange conduits, a chamber interconnectingsaid conduits, and means associated with the inlet conduit forcumulatively heating vapor therein as it approaches said chamber.

51. A fluid inlet conduit, a chamber at. the discharge end thereof,means for progressively increasing the heat. of fluid in said conduit,and means for returning the heated fluid from the chamber along theoutside of the conduit.

52. A fluid inlet conduit, a chamber at the discharge end thereof, meansfor progressively increasing the heat of fluid in said conduit, andmeans for returning the heated fluid from the chamber around the outsideof the conduit.

53. A member constructed to form a fluid conduit, means forprogressively heating a fluid as it passes therethrough, a casingforming a chamber adapted to receive the heated fluid at the dischargeend of the conduit, and providing means for returning the fluid fromsaid chamber along the outside of the conduit.

54. A member constructed to form a fluid conduit, means forprogressively heating a fluid as it passes therethrough, a casingforming a chamber adapted to receive the heated fluid at the dischargeof the conduit to form' 'a heat exchange jacket surrounding the conduit.

55. A fluid inlet conduit, a chamber at the discharge end thereof, meansfor progressively increasing the heat of fluid in said conduit, means insaid conduit for breaking up the fluid and retarding the flow thereof,and means for returning the heated. fluid from the chamber around theoutside of the conduit.

56. A member constructed to form a fluid conduit, means forprogressively heating a fluid as it passes, therethrough, a casingforming a chamber adapted to receive the heated fluid at the dischargeof the conduit to form a heat exchange jacket surrounding the conduit,and means in said conduit and jacket for breaking up the fluid andretarding the flow thereof.

In Witness whereof I have hereunto set my hand this 18 day of May, 1917WILLIAM S. HADAWAY, J R.

